A conventional socket can only engage with an object having a fixed size. If the user chooses a wrong socket which has an incorrect size, a smaller object or a larger object cannot be engaged with the socket. Therefore, the user has to prepare many sockets with different sizes so as to tighten or loosen objects having various sizes. It is understandable that when facing many objects with different sizes, the processes of choosing correct sockets, engaging the sockets with the right objects, and removing the sockets from the objects are time-consuming.
The present invention intends to provide a socket which has two open ends and each open end is able to engage with at least two objects with different sizes so that the user can only carry some sockets with him/her and can handle many situations of tightening or loosening objects. The present invention is able to mitigate the disadvantages of the conventional sockets.